U.S. Pat. No. 3,948,048 (Lifka) relates to a fluid drive which has a three coaxial cylinders, the outer of which is fixed to an output shaft and the inner to an input shaft. The intermediate cylindrical member has vanes on either side for interaction with vanes on the outer and inner cylinders. The action is described basically in lines 52 to 62 of column 2 of the specification and may be shortly described as follows:
rotation of the input shaft 24 causes rotation of cylinder 12, PA0 its vanes 29 cause the fluid in space 42 to rotate and, PA0 its vanes 25 then cause the cylinder 14 to rotate.
The fluid is trapped in the casing and the rotational forces cause frictional action or viscous drag on the vanes thus imparting the desired rotation.
In the present invention, the inefficiency of this type of action is recognized and reliance is placed on hydrodynamic principles involving changes in angular momentum, which allow for more efficient transfer of forces. The fluid is not trapped in the spaces between successive cylinders but rather is given an inwardly or outwardly directed motion so that the desired changes in angular momentum are realized.
U K Patent 607 4365 (Lombardini) is a similar arrangement to that of Lifka if one dissociates oneself with the clutch portion of the arrangement. In essence this invention is a combination of clutch and fluid transmission, the object being to maintain efficiency of the transmission on slipping of the clutch. In FIG. 2 of the Lombardini patent an arrangement very similar to that of Lifka is shown in so far as concentric sets of vanes are provided to "throw out the transmission fluid into the adjacent set of oppositely inclined vanes" from inside to outside (or vice versa). There are three sets of vanes for the driving member and two for the driven member.
U.S. Pat. No. 1,428,586 (Garrison) also provides an annular fluid channel with series of annular blades for frictional transmission of power from the driving to the driven shaft.
Swiss patent 86251 may appear at first glance to involve all angular impingement action by virtue of the provision of an inlet (g) and an outlet (h) for the fluid. However, it is clear that these are merely for the drainage of fluid and refilling purposes. Reference to FIG. 1 will show that the action is similar to all of the above inventions i.e. that of viscous drag, the fluid of these prior inventions moving with the shafts and their vanes and not, as in the stepless transmission system of the present invention, interacting with concentric cages allowing for the required changes in angular momentum.